In the past, panoramic viewing was accomplished using a plurality of sensors with each sensor disposed at a given angle so that the total sensing fields of the sensors together completed a three hundred sixty degree view. Such a sensor array was problematic in that each of the plurality of sensors used needed to be individually connected to a controller responsible for piecing together the individual fragments of the overall panoramic view attempted to be scanned. This involved numerous electrical connections and considerable cost in manual labor.
Thus it is an object of the invention to accomplish what has otherwise been done through using numerous sensors in an array using a single optical three hundred sixty degree optical lens type sensor. by way of background it should be understood that the primary function of a telescope is to enlarge the apparent size of a distant object. This is accomplished by presenting to the eye an image which subtends a larger angle (from the eye) than does the object. The magnification, or power, of a telescope is simply the ratio of the angle subtended by the image to the angle subtended by the object. Nominally, a telescope works with both its object and image located at infinity; it is referred to as an a focal instrument, since it has no focal length. In practice, departures from these infinite conjugates are the rule, but for the most part they may be neglected. However, one should be aware that when the object and or the image are not at infinity, this will occasionally have a noticeable effect and must then be taken into account. This is usually important only with low-power devices.
There are three major types of telescopes: astronomical (or inverting), terrestrial (or erection), and Galilean. An astronomical or Keplerian telescope is composed of two positive (i.e., converging) components spaced so that the second focal point of the first component coincides with the first focal point; the eyelens then reimages the object at infinity where it may be comfortably viewed by a relaxed eye. Since the internal image is inverted, and the eyelens does not reinvert the image, the view presented to the eye is inverted top to bottom and reversed left to right.
In a Galilean telescope, the positive eyelens is replaced by a negative (diverging) eyelens where the focal points of objective and virtual focus of the negative eyelens coincide. In the Galilean scope, however, the internal image is never actually formed; the object for the eyelens is a "virtual" object, no inversion occurs, and the final image presented to the eye is erect and unreversed. Since there is no real image formed in a Galilean telescope, there is no location where cross hairs or a reticle may be inserted.
The present invention in its preferred embodiment uses reverse Galilean, telescope type arrangements, front negative element and rear positive element, to effect sensing as will become apparent from the following disclosure.
Accordingly, it is an object of the invention to provide a sensing head which is capable of covering a view of approximately .+-.30 degrees from the horizon and 360 degrees all round.
A further object of the invention is to provide a sensor of the aforementioned type which maintains good wavefront qualities of the transformed beam.
Still a further object of the invention is to provide a sensor of the aforementioned type which transforms a wide panoramic view into a narrower forward looking view that a single sensor can accept.